1. Field of the Invention
The present invention relates to an effect adding apparatus which is capable of adding various sound effects to audio signals input from an electronic musical instrument and other audio equipment.
2. Description of the Related Art
In an electronic musical instrument and audio equipment which generate and process sounds, it has been an important theme how to generate musical tones of rich tone color. A conventional electronic musical instrument and audio equipment generate musical tones which are richer in sound effects with the aid of effector devices which add sound effects such as chorus, delay, reverberation effects and the like to the generated musical tones.
In recent, a so called multi-effector which is capable of simultaneously adding a plurality of sound effects to musical tones has been proposed and put in use in place of an effector which adds a single sound effect to musical tones.
The multi-effector includes a plurality of effectors which add a single sound effect to musical tones. The multi-effector is composed of a series connection of effectors or a parallel connection of effectors, or is composed of a digital signal processor (DSP), to which a program involving algorithms for performing various effect processes is sent to obtain a plurality of sound effects.
Furthermore, when the multi-effector is used as an effect adding device in an electronic musical instrument, the method of playing the musical instrument is changed to alter an atmosphere of musical tones to be generated, but lately some trials have been made to realize the above by changing a way to apply the sound effects to musical tones or changing the number of sound effects to be applied to the musical tones.
In the conventional effect adding device including a plurality of effectors, however, the physical connection of those effectors must be changed. But it will be easily understood that it is extremely hard to change the physical connection of the effectors while a performance of the musical instrument is being effected, and the effect adding device will not exhibit its features as the multi-effector to a full extent. Usage of a switch may be also proposed for switching the connections of the effectors during the performance of the musical instrument, but a complicated circuitry arrangement will be invited for that purpose.
Meanwhile, when a user operates the multi-effector composed of DSP, he is simply required to change a program to be input thereto to obtain various sound effects, but a sufficient number of algorithms must be prepared in advance for executing various effect processes combined in different ways, and a central processing unit (CPU) consequently needs a large capacity of memory for storing the algorithms to be transferred to the DSP.
Some effects of superior features may be realized by an analog effect adding device using analog elements, rather than by the DSP executing a digital process. A distortion effect for distorting an input audio signal is one example of such effects. The reason why the analog effect adding device is preferably used in place of the digital effect adding device is that the analog effect adding device employs an analog element (for example, a diode) which is of a non-linear characteristic to add the distortion effect to an input signal while the digital effect adding device has inherently limited features to precisely exhibit the fine non-linear characteristic.
To include specific effects which will be expressed more efficiently by the analog effect adding device to the effects of the multi-effector, some trials have been made to generate musical tones of higher tone quality, in which an analog process is used to obtain specific effects and also digital processes are used to realize other effects. As a result, a multi-effector has been proposed which comprises a DSP for generating digital effects and an analog effect adding device for generating analog effects, both being physically connected with each other.
With the above structure of the multi-effector, however, an order of applying effects to a musical tone is limited by the physical connection of the DSP and the analog effect adding device, so that the order of application of sound effects to a musical tone can not be changed easily.
For example, when the distortion effect is added to a musical tone by the analog effect adding device and other effects are added by the DSP, and effects are added to tones in the order of reverberation, chorus, echo, and distortion effects, the analog effect adding device may be connected to the output of the DSP. To change the above order of the effects to such order as chorus, echo, distortion and reverberation effects, two units of DSPs must be prepared and an analog effect adding device are connected in series in the order of the DSP, the analog effect adding device and the DSP. The first DSP is arranged to execute the chorus and echo processes, and the following analog effect adding device executes the distortion effect, and finally the last DSP performs the reverberation effect.
With the above multi-effector including a connection of the analog effect adding device and the digital effect adding devices, the order of the physical connection of these two types of effect adding devices must be changed to alter the order of addition of various effects, which prevents the multi-effector from being used often and conveniently.